In the manufacturing process of a semiconductor device or the like, there has been a process of forming an electrode by forming a trench and hole-shaped groove (contact hole) in an interlayer insulating film on a silicon substrate, and by embedding a silicon film (Si film) such as a polysilicon film, an amorphous silicon film, and a polysilicon film and an amorphous silicon film doped with impurities.
In such a process, for example, there has been proposed a method of forming a contact hole in the interlayer insulating film on the silicon substrate, forming the polysilicon layer using a CVD (Chemical Vapor Deposition) method, and forming the polysilicon film again after slight etching of the polysilicon film.
Due to the miniaturization of semiconductor devices, the aspect ratios of the trenches in which Si film is embedded has been increasing. Due to higher aspect ratios, voids can occur when the Si film is embedded. The voids may degrade the Si film's performance as an electrode.
Particularly, when an Si film doped with phosphorus (P) is embedded in a contact hole and its surface roughness is not satisfactory, there is a problem in that seams, voids, or the like may easily occur. This problem is particularly severe when the Si film is doped with high concentrations of P.